Haeckel's Law — 67 — Hereditary 



Haploid-insufficient. — Used of duplicate genes to indicate 

 that neither of them will, in the heterozygous state, give full 

 expression to the character; incompletely dominant. 



Haploid Parthenogenesis. — See under Parthenogenesis. 



Haploid-sufHcient. — Used of duplicate genes to indicate 

 that either of them, in the heterozygous state, gives full ex- 

 pression to the character; completely dominant. 



Haplomict. — A hybrid carrying a single genom made up of 

 chromosomes and portions of chromosomes from different 

 sources. (Occurs in certain algae and bryophytes). 



Haplomitosis. — Type of cell division where nuclear granules 

 form chromospires which withdraw in two groups or divide 

 transversely in the middle (Henderson). 



Haplont. — A plant in which fertilization is followed imme- 

 diately by a reduction division so that all nuclei, other than 

 the zygotic nucleus, are haploid, e.g. most fungi and algae. 



Haplontic Sterility. — Sterility due to the production of de- 

 generate non-functional gametes; gametic sterility. 



Haplophase. — The stage in the life-cycle of an organism 

 when the nuclei contain the haploid number of chromosomes. 



Haplosis. — The halving of the somatic chromosome number 

 at meiosis. 



Haplostemonous. — Possessing only one whorl of stamens. 



Haplozygous. — Hemizygous, q.v. 



Hardy's Formula. — If AA and aa individuals are mixed in 

 the proportion of q and 1-q respectively, then in a population 

 in which random mating is the rule, the population in all 

 subsequent generations will consist of: q^AA : 2q (l-q)Aa: 

 (l-q)2aa. 



Heat. — The period of sexual excitement in female animals 

 during the breeding season. 



Hemeranthic. — Flowering by day. 



Hemikaryon. — A haploid nucleus. 



Hemikaryotic. — With half the somatic number of chromo- 

 somes; haploid. 



Hemizygous. — Of a gene: present in the unpaired state, as 

 in haploid organisms, or in an unpaired sex chromosome, or 

 in a differential segment of a sex chromosome. 



Hercogamy. — The state of being incapable of self-fertiliza- 

 tion owing to the position of the stamens in relation to the 

 stigma or stigmas. 



Hereditary. — (i) In the clinical sense: transmitted with un- 

 broken continuity from generation to generation, (ii) In the 

 genetic sense: controlled by a genetic mechanism which is 



